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LoRaWAN® Gateways: Radio Coexistence Issues and Solutions

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LoRa Alliance ® Whitepaper Page 31 of 49 LoRaWAN ® Gateways Radio Coexistence Issues and Solutions Copyright ©2021 LoRa Alliance, Inc. All rights reserved. www.lora-alliance.org 3.9 SUMMARY Colocation of LoRaWAN gateways with LTE BS imposes several constraints on the gateway installation and design: • At least 45dB isolation is required between the LTE BS antenna and LoRa antenna to minimize impact of LTE BS out-of-band spurious emissions. • A minimum attenuation of 57dB (60dB) of the LTE BS DL band is expected from Rx RF filters of the LoRaWAN gateways, to mitigate LTE BS blocking. • A minimum IIP3 of -33dBm for the LoRaWAN receiver is required to mitigate LTE BS intermodulation. • A minimum attenuation of 40dB of LTE BS UL/DL band is expected of the LoRaWAN Tx path, between the PA and antenna port, to reduce transmitted out-of-band spurious emissions and minimize the transmit intermodulation. The minimum separation distance between an LTE BS and a LoRaWAN gateway equipped with a 6dBi LoRa antenna is summarized in this table: Gateway Type Min. Vertical Separation for Wide- area BS (48dBm) Min. Vertical Separation for Medium- range BS (38dBm) Min. Horizontal Separation for Wide- area BS (48dBm) Min. Horizontal Separation for Medium- range BS (38dBm) Recommendation EU868-870 version 1m 1m 150m 150m Cavity filter US902-928 version 1m 1m 150m 40m Cavity filter AU915-928 version 1.5m 1m 200m 150m Cavity filter AS923 version Guard band <2MHz 100m 40m 10km 7km Cavity filter + increase guard band AS923 version Guard band <5MHz 7m 2.5m 1500m 400m Cavity filter + increase guard band AS923 version Guard band <10MHz 1.5m 1m 200m 150m Cavity filter A cavity filter is recommended in all use cases, as detailed in the last column. The cavity filters are described in §7. For AS923 versions of the gateway, it is recommended to add a cavity filter (see §7) and increase the guard band between the LoRaWAN channels and the edge of the LTE UL band. A guard band of 2MHz or less must be avoided unless accepting huge desensitization of the LoRaWAN gateway and significant reduction of the coverage area.

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